Emphasis has been placed on characterizing crystallin genes. Two delta-crystallin genes with 14 to 15 intervening sequences have been identified and analyzed in genomic clones derived from chickens. Clones of alpha-, beta-, and gamma-crystallin cDNAs have been obtained from mice and are being characterized in order to study the corresponding genes in this organism. One beta-crystallin polypeptide has been shown to be synthesized exclusively in elongating lens cells suggesting differential expression of the beta-crystallin genes during fiber cell differentiation. Spectroscopy studies have demonstrated age-dependent changes in the conformation of gamma-crystallin in chickens. Experiments with virally-infected lens epithelial cells have dissociated changes in cell growth and morphology from gamma-crystallin gene expression. Finally, the initial reduction of crystallin synthesis in two hereditary cataracts in mice has been shown to be associated with poor utilization of persistant crystallin mRNAs due, at least in part, to an increase in K ion and decrease in Na ion within the lens.